A known pulse width modulated (PWM) inverter includes a center tapped power supply with positive and negative terminals, the center tap being connected to neutral or ground. The positive and negative terminals are connected to a low pass output filter through respective switches which may be transistors or the like. The inverter switches are controlled to alternately conduct current to the output filter, the switches providing a pulse width modulated waveform to the filter, which in response thereto, provides an AC output which is applied to a load.
The pulse width modulated waveform applied to the output filter typically has a voltage swing of the rail-to-rail voltage of the inverter power supply over each half-cycle of the output. In order to provide the desired AC output, a very large output filter is typically required to accommodate the large rail-to-rail voltage swing of the pulse width modulated waveform from the inverter. Where the inverter is to be used in applications where weight is critical, such as on an aircraft, the use of such large filters is extremely undesirable.
Another problem with known PWM inverters is their capacity to accept regenerative currents. In applications where the load is reactive, the power supply of the inverter typically includes capacitors for accepting all regenerative currents. Even with a near unity power factor load, if the load current is continuous because of the output filter, the capacitors must still accept regenerative currents. The power supply capacitors must therefore be quite large, increasing the weight of the inverter which is undesirable for many applications.